Process for the production of a carbon monoxide containing gas

ABSTRACT

A process for producing carbon monoxide and hydrogen which comprises contacting a carbon dioxide containing gas with a carbonaceous material in the presence of a cesium salt catalyst in a reaction zone operating at temperatures below 1,600* F.

United States Patent 1 1 Buben et al.

1451 Sept. 11,1973

PROCESS FOR THE PRODUCTION OF A CARBON MONOXIDE CONTAINING GASlnventors: David Buben; Clyde L. Aldridge,

both of Baton Rouge, La.

Esso Research and Engineering Company, Linden, NJ.

Filed: Mar. 18, 1971 Appl. No.: 125,582

Assignee:

US. Cl 423/415, 423/656, 252/441, 252/443 Int. Cl...... C0lb 31/18, COlb1/08, COlb l/O2 Field of Search 23/204, 213, 210; 423/415, 439

References Cited UNITED STATES PATENTS 1/1960 Johnson et al. 23/204 MlOl 103 CATALYST 3,385,668 5/1968 Schunemann ..23/2()4M 3,539,2971l/197O Aldridge 1 23/213 3,615,216 10/1971 Aldridge 23/213 PrimaryExaminer-Edward Stern Attorney-Pearlman & Schlager and Llewellyn A.

Proctor [57] ABSTRACT A process for producing carbon monoxide andhydrogen which comprises contacting a carbon dioxide containing gas witha carbonaceous material in the presence of a cesium salt catalyst in areaction zone operating at temperatures below 1,600 F.

5 Claims, 1 Drawing Figure I14 L CARBON MONOXIDE FlRST REACTION X sscouoEACTlON v ZONE ZONE CARBON SOURCE CARBON DIOXIDE Patgnted Sept; 11, 1973mwmmzmom MQXOE zommdu wzon 2964mm 5%.

INVENTORS DAVID BUBEN CLYDE L. ALDRIDGE wumDOm 20mm u PROCESS FOR THEPRODUCTION OF A CARBON MONOXIDE CONTAINING GAS BACKGROUND OF THEINVENTION This invention relates to the production of carbon monoxideand hydrogen. More particularly it relates to the production of carbonmonoxide by a process where carbon dioxide is contacted with carbon inthe presence of a catalyst composition in a reaction zone operated at atemperature less than l,600 F.

In another aspect this invention relates to the production of synthesisgas. More particularly, the carbon monoxide produced in a first reactionzone by reacting carbon dioxide with carbon in the presence of acatalyst is introduced, along with steam, into a second reaction zone soas to contact a water gas shift reaction catalyst to produce a hydrogencontaining gas.

It has been known that carbon monoxide could be produced by reactingcarbon dioxide with a carbonaceous material according to the followingreaction:

However, this process must be carried out underextreme conditions. Inorder that these conditions, particularly temperature, could be reducedvarious catalysts have been employed. Although the above reaction in thepresence of certain catalysts could proceed at temperatures about l,000F., it was not until temperatures of about 2,000 F. were reached in thereaction zone that high enough rates of conversion of carbon and COconversion to carbon monoxide were obtained for the process to becomeeconomically feasible. However, to maintain the reaction zone at suchextreme temperatures requires a large heat input which is veryexpensive. Furthermore, such extreme temperatures result in engineeringproblems in the construction of reaction vessels used in this process.As a result such vessels are very expensive capital expenditures. 7

As it would be desirable to have lower cost carbon monoxide to use inother petroleum processes such as the production of hydrogen by reactingsteam with carbon monoxide, it is accordingly an object of thisinvention to provide a process for more economically producing carbonmonoxide.

A further object of this invention is to produce carbon monoxide byreaction of carbon dioxide and carbon at temperatures much less than2,000 F.

Another object of this invention is to provide an improved carbon-carbondioxide reaction catalyst.

These and other objects will become apparent from the ensuingdescription of the invention.

SUMMARY OF THE INVENTION Carbon monoxide is produced in a reaction zoneoperating at temperatures'between 1 ,000 and 1,600 F., preferablybetween 1,400 and l,600 F., and at pressures between and 1,000'psig bypassing carbon dioxidc through a carbonaceous material, preferably petroleum coke, at a rate between 0.1 and 10.0 moles CO,/- mole C/Hr.,preferably between 0.1 and 4.0 moles CO /mole C/Hr,, in the presence ofan alkali salt catatemperature between 300 and 900 F. and a pressurebetween 0 and 1,000 psig and which also contains a water gas shiftcatalyst.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE schematically illustratesthe preferred embodiment of this invention.

PREFERRED EMBODIMENT OF THIS INVENTION As stated above a critical needin todays refinery processes is the need for an economical source ofhydrogen. It is known that carbon reacts with carbon dioxide to producecarbon monoxide C+CO 2C0,

and that carbon monoxide can be treated with steam to produce hydrogenand carbon dioxide The hydrogen so produced could be recovered and usedin other refinery processes such as hydrofining, etc. The carbon dioxidecould be then recycled over a carbon containing material to produce morecarbon monoxide. Such a process appears even more attractive since thereexist in refinery operations certain materials such as high sulfurpetroleum coke, etc. which have little economic value as products, butwhich have high carbon contents. Thus a cheap source of carbon isreadily available.

However, until now such a process was not economically attractive sincethe reaction could not be carried out and produce sufficient quantitiesof carbon monoxide to be economically attractive unless reactiontemperatures of about 2,000 F. could be used. g

According to this invention CO, ispassed through a carbonaceous materialsuch as petroleum coke, charcoal, graphite, coal char, or any othersolid carboneontaining material, but preferably petroleum coke, in thepresence of a cesium salt catalyst, all of which are in a reaction zone.

Although any heavy carbonaceous material may be used the preferredembodiment will be described using petroleum coke. I

Petroleum coke is introduced through line 102 into reaction zone 101which is operating at a temperature between 1,000 and 1,600? F.,preferably between by preheating the petroleum coke before it is placedinto the reaction zone or it may be heated by electrical or other meansonce it is in the reaction zone.

lyst, preferably cesium carbonate, or molten alkali salt meltscomprising cs,co,.

In another embodiment of this invention a hydrogen-- A cesium saltcatalyst, preferably cesium carbonate, is also introduced through line103 into reaction zone 101. This catalyst could comprise cesium formate,cesium acetate, or any other cesium salt that will decompose into cesiumcarbonate when in the presenceof CO or CO, at temperatures between 1,000and 1,600 F. The preferred catalyst is cesium carbonate since thehighest carbon-carbon dioxide conversion rates at lower .temperaturesare obtained with this catalyst. Of course, the catalyst could becomprised of mixtures of the different cesium salts described above, orit could also be comprised principally of cesium carbonate and lesserweight amounts of other alkali metal saltssuch as Li CO and CsCl. Whenusing certain alkali metal salts in combination with Cs CO such as Li COand CsCl, these mixtures are maintained as a molten salt melt and the LiCO and CsCl are used in amounts between 40 and 60 mole percent based onthe total catalyst weight because the use of a melt aids in the catalystrecovery, results in more efficient heat transfer from the catalyst tothe feed, and makes possible lower operating temperatures in thereaction zone.

The amount of catalyst needed in the reaction zone is dependentprimarily upon the operating conditions of the reaction zone. Generallya catalyst content of between and 1,000 weight percent based on theamount of carbon will give satisfactory carbon conversion rates.

Carbon dioxide is then introduced through line 104 into reaction zone101 so as to contact the petroleum coke in the presence of the cesiumsalt catalyst. The carbon dioxide is introduced into the reaction zoneat a rate dependent on the amount of carbon in the zone. Rates of 0.l to10.0 moles CO /mole C/Hr., preferably 0.1 to 4.0 moles Co /mole C/Hr.,and most preferably 0.1 to L0 moles Co /mole C/Hr., will give excellentcarbon-carbon dioxide conversion rates.

If it is desired to produce more hydrogen for use in other refineryprocesses the carbon monoxide produced in reaction zone 101 under theabove described conditions can be removed from reaction zone 101 by line105 and introduced into second reaction zone 106 containing a water gasshift catalyst so as to react with steam introduced through line 107.

Suitable shift catalysts include iron or copper on an alumina support,copper-zinc oxide, and the like. When such catalysts are used thereaction in zone 106 may be carried out at temperatures between 300 and900 F., and pressures between 0 and 1,000 psig. Under these conditionssteam will be introduced in amounts greater than the CO present.

The gaseous products from reaction zone 106 are removed from said zoneby line 108 and introduced into a scrubber reactor 109 where steam andcarbon dioxide are removed. The CO can be recycled after removal ofsteam by conventional means not shown to the first reaction zone by line110 and 104.

There are many known processes for removal of steam and carbon dioxidefrom hydrogen containing gases. The steam may be condensed and removedwhile the carbon dioxide may be removed by many processes such as thestandard water scrubbing process, use of ethanolamines, use of hotpotassium carbonate as a scrubbing agent, Fluor solvent process (US.Pat. No. 2,926,75 l Giammarco-Vetrocoke hot carbonate process (ItalianPat. No. 470,758), or the Catacarb process [A. G. Eickmeyer, ChemicalEngineering Progress, 58(4), pp. 89-9], (l962)].

The hydrogen and carbon monoxide are taken from the scrubber reactor 109byline 111 and introduced to a typical carbon monoxide separator vessel112 wherein the hydrogen gas is separated from the carbon monoxide andremoved by lines 113 and 114 respectively. Typical of such carbonmonoxide separation processes would be either the copper-liquorscrubbing process or the low temperature separation as described involume 4 of Kirk-Othmer Encyclopedia of Chemical Technology at pages438-440. The hydrogen so recovered may then be sent to the desiredpetroleum processing operation and the carbon monoxide may be recycledto the second reaction zone 106. Alternatively the residual carbonmonoxide could be removed from the hydrogen by conventionalmethanization.

The following examples are provided to illustrate the process as abovedescribed and to demonstrate the superiority of this process over otherknown processes.

Example I illustrates the most preferred aspect of this invention.Example II illustrates the results obtained when using othercarbonaceous material than coke, and at different operating conditions.

EXAMPLE I Fluid petroleum coke which had the following composition:

Weight Carbon Weight Hydrogen 2.02 Weight Sulfur 6.39 Weight Nitrogen1.49 Weight Oxygen 3.30 Weight Vanadium 0.05 Surface Area (M /g.) 1 L0Pore Volume (ML/g.) 0.0

Carbon Carbon Dioxide Conversion Rate Conversion /Hr.) Uncatalyzed l. l3 .4 Cs CO; Catalyst 14.! 63.7

This dramatically illustrates the effect of adding a Cs CO catalyst tothe reaction zone. It is seen that the reaction rate is enhanced byl0-20 fold both as measured by carbon conversion rate and degree ofcarbon dioxide conversion.

EXAMPLE n The same procedure as in Example I was repeated except thetemperature, pressure, C0 gas rate, and feed were varied. In some cases,activated coconut charcoal was used as the feed. Activated coconutcharcoal (20-70 mesh) refers to a carbonaceous materialcomprised of thefollowing components:

- Weight 16 Carbon 89.80 Weight Hydrogen 0.52 Weight Sulfur 0.10 WeightNitrogen -0.00 Weight Oxygen 9.58 Weight Vanadium -0.00 Surface Area(Mlg) H Pore Volume (ML/g.) 0.75

The results of these runs follow.

CO2 gas Amount Q0 rate of conversion production Reaction (mole CszCOrCarbon (percent 1" e temper- Reaction (302/ (wt. conversion at max.(moles Carbon 1 aturo pressure mole percent (percent/ carbon (JO/molematerial F.) (p.s.i.g.) C/hr.) on feed hr.) converslon) C/hr.)

Run Number:

1 1, 000 0 3. 71 100 2. 28 0. 77 0. 057 1, 000 650 3. 71 100 0. 64 O. 21O. 016 1, 000 650 3. 71 100 2. 20 O. 71 0. 053 1, 400 O 1. 24 None 0. 900. 71 0. 018 1, 400 0 1. 02 24 26. 60 25. 20 0. 515 1, 400 O 1. 03 None2. 82 2. 53 0. 052 1, 400 0 1. 00 24 35. 80 35. 1 0. 702 1, 500 0 0. 30None 1. 08 3. 4 0. 020 1, 500 0 0. 22 24 12. 40 56. 7 0. 249 1, 500 0 0.044 24 3. 48 83. 8 O. 0738 1, 500 0 0. 24 24 14. 10 63. 7 0. 306 1, 5000 0. 56 24 33. 7 40. 0. 454 1,500 0 1. 93 24 51. 5 26. 7 1. 03

1 FPC=t1uid petroleum coke; ACO =Activated coconut charcoal.

From the above data, it is seen that the preferred operatingtemperatures are above 1,400 F. and most preferably around l,500 F.

We claim:

I. A process for the production of a carbon monoxide-containing gas froma carbonaceous material, which comprises:

contacting a carbon dioxide-containing gas with a carbonaceous materialat a rate between 0.1 and moles CO per mole C per hour in the presenceof a catalyst composition comprising a molten mixture of cesiumcarbonate with lithium carbonate or cesium chloride, wherein the lithiumcarbonate or the cesium chloride comprises from about 40 to about 60mole percent of the total weight of said catalyst composition, in areaction zone maintained at a temperature between about l,000 and aboutl,600 F. and at a pressure between about 0 and 1,000 psig.

2. A process for the production of a carbon monoxide-containing gas froma carbonaceous material,

which com r i s e si contacting carbon dioxide with a carbonaceousmaterial at a rate between 0.1 and 10 moles CO per mole C per hour inthe presence of a catalyst composition comprising a molten mixture ofcesium carbonate with lithium carbonate or cesium chloride,'wherein thelithium carbonate or the cesium chloride comprises about 40 to aboutmole percent of the total weight of said catalyst composition, in areaction zone maintained at a temperature between about l,400 and L600F. and at a pressure between about 0 and 650 psig.

3. The process of claim 2, wherein said carbon dioxide is introducedinto said reaction zone at a rate of 0.1 to 4 moles CO per mole C perhour.

4. The process of claim 2, wherein said carbon dioxide is introducedinto said reaction zone at a rate of 0.1 to 1 mole C O per mole C perhour.

5.'The process of claim 2, wherein said carbonaceous material ispetroleum coke.

2. A process for the production of a carbon monoxide-containing gas froma carbonaceous material, which comrises: contacting carbon dioxide witha carbonaceous material at a rate between 0.1 and 10 moles CO2 per moleC per hour in the presence of a catalyst composition comprising a moltenmixture of cesium carbonate with lithium carbonate or cesium chloride,wherein the lithium carbonate or the cesium chloride comprises about 40to about 60 mole percent of the total weight of said catalystcomposition, in a reaction zone maintained at a temperature betweenabout 1,400* and 1,600* F. and at a pressure between about 0 and 650psig.
 3. The process of claim 2, wherein said carbon dioxide isintroduced into said reaction zone at a rate of 0.1 to 4 moles CO2 permole C per hour.
 4. The process of claim 2, wherein said carbon dioxideis introduced into said reaction zone at a rate of 0.1 to 1 mole CO2 permole C per hour.
 5. The process of claim 2, wherein said carbonaceousmaterial is petroleum coke.